1. Field of the Invention
The present invention relates to a back-up table for a chip mounter, and more particularly, to a back-up table for a chip mounter used in equipment for supporting a printed circuit board on a certain position in the chip mounter.
2. Description of the Related Art
In general, a chip mounter is a device for mounting small electronic components such as a semiconductor chip on a printed circuit board. The chip mounter picks up electronic components supplied through a component supply device using a pickup mechanism movable on an X- and Y-axis frame, and then mounts the components onto the printed circuit board conveyed by a board conveyance device.
When the electronic components are completely conveyed to a mounting position by the board conveyance device, the printed circuit board is raised to a predetermined position by a back-up table disposed under the printed circuit board. Then, the pick-up mechanism moves onto the printed circuit board, and a suction means is lowered onto the printed circuit board to mount the electronic components on the printed circuit board.
FIG. 1 is a front view of a conventional back-up table for a chip mounter. The conventional back-up table for a chip mounter includes an upper table 1 on which a printed circuit board (not shown) is mounted, a lower table 2 disposed under and spaced apart from the upper table 1, and a pneumatic cylinder 3 installed at the lower table 2 to raise/lower the upper table 1.
In addition, a guide part 4 is installed at edge parts of the upper table 1 and the lower table 2. The guide part 4 includes a plurality of guide rods 5 fixed to a lower surface of the upper table 1, and a plurality of guide holes 6 formed in the lower table 2 and through which the guide rods 5 pass.
Here, the pneumatic cylinder 3 is disposed at center parts of the upper and lower tables 1 and 2. One end of a rod 3a of the pneumatic cylinder 3 is fixed to the lower surface of the upper-table 1. In addition, the guide part 4 is disposed at the edge parts of the upper and lower tables 1 and 2.
However, in the conventional back-up table for a chip mounter as described above, horizontality of the upper table generally cannot be maintained upon upward movement of the upper table, and therefore the printed circuit board cannot be uniformly supported.
Korean Utility Model Registration No. 131578 discloses another back-up table for a chip mounter. That is, the utility Model discloses technology using a stepping motor and a raising/lowering device mechanically connected to the stepping motor to variously adjust the height of the back-up table without using a pneumatic cylinder. However, the conventional back-up table for a chip mounter has disadvantages of complicating the entire structure and increasing the entire manufacturing cost.